Q61.The two spheres 2 2 2 x y z 25 and 2 2 2 x y z 18x 24y 40z 225 0 + + − − − + = + + − − − + = + + − − − + = + + − − − + = touch at some point. the point of contact is–
Correct answer: 9 12,,4 5 5
Q62.The centre of the sphere (x 1)(x 3) (y 2)(y 4) (z 3) (z 1) 0 is + + + − − + + + + + − − + + + + + − − + + + + + − − + + + = − + = − + = − + = −
Correct answer: (–2, 3, –2)
Q63.The cone reciprocal to the cone 2 2 2 ax by cz 0 is–
Correct answer: 2 2 2 x y z 0 a b c
Q64.The equation of the sphere whose centre is (2,–3, 4) and the radius 5 is–
Correct answer: 2 2 2/x y z 4x 6y 8z 4 0
Q65.The equation of the circular cone, which contains the three co-ordinate axes as generators, is–
Correct answer: None of the these
Q66.The vertex of the cone 2 2 2 2x 2y 7z 10yz 10zx 2x 2y 26z 17 0, is–
Correct answer: (2,2,1)
Q67.The plane 2x y z 12 + + = + + = + + = + + = touches the 2 2 2 x y z 24 + + = + + = + + = + + = sphere at the point
Correct answer: (4,2, 2)
Q68.Two spheres of radii 3 and 4 cut orthogonally. The radius of the common circle is:
Correct answer: 12/5
Q69.The value of 'a' for which the plane x + y + z = a 3 touches the sphere x2 + y2 + z2 – 2x – 2y – 2z – 6 = 0 will be:
Correct answer: 3 + 3
Q70.The radius of the sphere x2 + y2 + z2 – 2x – 10y – 2z + 2 = 0
Correct answer: 5
Q71.If the plane 2x – y + az = 0 cuts the cone yz + zx + xy = 0 in perpendicular lines, then the value of a is:
Correct answer: 2
Q72.The radius of the circle x2 + y2 + z2 + x + y + z– 4 = 0, x + y + z = 0 is:
Correct answer: 2
Q73.The radius of the sphere 4(x2 + y2 + z2) – 16x + 20y – 32z + 5 = 0 is:
Correct answer: 5
Q74.If the equation αx2 +βy2 +2z2 –2αx–4βy–40 = 0 represents a sphere, its radius is:
Correct answer: 5
Q75.If the equation x2 –y2 +z2 –4x+2y+6z+λ=0 Represents a cone, then the value of λ is equal to:
Correct answer: 12
Q76.The pole of the plane 3x+4y+5z = 6 with respect to the sphere x2 +y2 +z2 = 12, is:
Correct answer: (6, 8, 10)
Q77.The radius of the circle in which the sphere x2 +y2 +z2 –8x+4y+8z–45 = 0 is cut by the plane x–2y+2z = 3, is:
Correct answer: 4 5
Q78.The angle between the line joining the centers of two spheres and there radical plane is–
Correct answer: 2
Q79.Which one of the following equations represents a cone not having three mutually perpendicular generators:
Correct answer: 2 2 2/x 2y 3z 0
Q80.the radius of the sphere 2 2 2 2x y z 2 x 6y 4 z 1 0 is–
Correct answer: 3 3/2